Ceramics range from diverse silicates to oxides of Al, Ti, Zr, Be, etc. Ceramics also include non-oxides such as carbides, nitrides and borides of the transition elements plus multiphase composites which may be totally or partially ceramic.
Ceramics may be used as electrical insulators, semiconductors, conductors or superconductors and may display large piezoelectric effect, have voltage-sensitive resistance or may have their electrical permittivity change with humidity. They may be good heat conductors or excellent thermal insulators and can be used at high operating temperatures intolerable by many metals and super alloys. Broadly speaking, the permissible operating temperature of ceramics is between about 0.5 to 0.7 Tm where Tm is the ceramic's melting point.
Although the synthesis of ceramic materials for high performance and high reliability is advancing tremendously, their commercialization is lagging due to poor integration techniques. While scientific and engineering efforts have been focused upon ceramic-metal joining/bonding, ceramic—ceramic bonding is not, as of yet, as well developed.
U.S. Pat. No. 5,769,997 to Akaike et al. and European Patent Specification 0619598 A3 0619598 to Akaike et al. both describe anodic bonding of an insulator containing no movable ion and a conductor through the medium of a conductive film and an insulator layer containing movable ions.
U.S. Pat. No. 5,695,590 to Willcox et al. describes anodic bonding to fabricate a pressure sensor.
U.S. Pat. No. 4,452,624 to Wohltjen describes a method for making an airtight seal between a pair of glass plates.
European Patent Specification 0317445 to Gotou describes bonding of a first silicon substrate coated with silicon oxide to a second silicon substrate coated with beta-SiC and/or phosphosilicate glass layer.